Option to disable autoplay of videos

[jsalort]

Is your feature request related to a problem? Please describe. In resource-limited setups, swiping fast between movies causes a strong lag (almost a DoS).

Describe the solution you'd like I'd like to have the option to disable autoplay of videos (there is already this option for live photos). So I can only play videos that I really want to play, and avoid spawning a number of ffmpeg processes everytime I am quickly swiping between media.